[D] Apsaravis ukhaana [~/~]
Describer
Norell & Clarke, 2001
Time
Cretaceous Late Campanian
Classification
Saurischia Theropoda Tetanurae Coelurosauria Maniraptora Avialae Ornithothoraces Ornithurae
Fossilsite
Djadochta Formation, Ukhaa Tolgod, Omnogov, Mongolia
Info
Partial postcranial skeleton.
Clarke, J. A., and Norell, M. A. (2002) The morphology and phylogenetic position of Apsaravis ukhaana from the Late Cretaceous of Mongolia: American Museum Novitates, n. 3387, 46pp.
Abstract: The avialan taxon Apsaravis ukhaana from the Late Cretaceous of southern Mongolia is completely described and its phylogenetic position is evaluated. Apsaravis ukhaana is from continental sandstones exposed at the locality of Ukhaa Tolgod, Omnogov Aimag, Mongolia.
The holotype specimen consists of the nearly complete, articulated skeleton of a small volant avialan. Apsaravis ukhaana is unambiguously differentiated from other avialans based on the presence of several unique morphologies: a strong tubercle on the proximal humerus, a hypertrophied trochanteric crest on the femur, and extremely well-projected posterior wings of a surface of the distal tibiotarsus that in Aves articulates with the tibial cartilage.
Ten other homoplastic characters optimize as autapomorphies of Apsaravis ukhaana in the phylogenetic analysis. They are as follows: ossified mandibular symphysis; dentary strongly forked posteriorly; hooked acromion process on scapula; highly angled dorsal condyle of humerus; humeral condyles weakly defined; distal edge of humerus angling strongly ventrally; humerus flared dorsoventrally at its distal terminus; lateral condyle of tibiotarsus wider than medial one; neither condyle of tibiotarsus tapering toward the midline; and metatarsal II trochlea rounded rather than ginglymoid. Phylogenetic placement of Apsaravis ukhaana as the sister taxon of Hesperornithes, Aves resulted from analysis of 202 characters scored for 17 avialan ingroup taxa. The implications of Apsaravis ukhaana, and the results of the phylogenetic analysis, for the evolution of flight after its origin and character support for enantiornithine monophyly are extensively discussed.
A. ukhaana was discovered during the 1998 field season of the Mongolian Academy of Sciences/American Museum of Natural History Paleontological Expeditions. It was recovered from the Camel’s Humps sublocality of Ukhaa Tolgod, a locality in the Nemegt Basin of southern Mongolia known for abundant, exquisitely preserved vertebrate fossils
Holtotype: IGM 100/1017. The holotype is a nearly complete skeleton in partial articulation articulation. It is comprised of the following elements: a crushed skull with a ring of scleral ossicles in the left(?) orbit; incomplete left quadrate, partial left jugal, partial mandible; 12 cervical vertebrae, 7 thoracic vertebrae; 10 ankylosed sacral vertebrae; 5 free caudal vertebrae; a pygostyle, fragmentary thoracic ribs; fragment of the anterior sternum, both scapulae; both coracoids, both humeri, ulnae, radii, radiale, right ulnare, partial right and left carpometacarpi, right phalanx one of manual digit II; ilia, ischia (right missing distal end); pubes (right, fragmentary); both proximal femora, both distal tibiotarsi; both tarsometatarsi (co-ossified metatarsals II–IV); incomplete series of pedal phalanges of digits II–IV from both feet. Several of these phalanges including three unguals were prepared apart from the main block and are preserved together in a separate, unfigured block. The distal end of the right humerus was removed from the block and prepared separately. Also, a small, midshaft section from the right radius was removed for study. (Clarke and Norell, 2002)
Norell & Clarke, 2001
Time
Cretaceous Late Campanian
Classification
Saurischia Theropoda Tetanurae Coelurosauria Maniraptora Avialae Ornithothoraces Ornithurae
Fossilsite
Djadochta Formation, Ukhaa Tolgod, Omnogov, Mongolia
Info
Partial postcranial skeleton.
Clarke, J. A., and Norell, M. A. (2002) The morphology and phylogenetic position of Apsaravis ukhaana from the Late Cretaceous of Mongolia: American Museum Novitates, n. 3387, 46pp.
Abstract: The avialan taxon Apsaravis ukhaana from the Late Cretaceous of southern Mongolia is completely described and its phylogenetic position is evaluated. Apsaravis ukhaana is from continental sandstones exposed at the locality of Ukhaa Tolgod, Omnogov Aimag, Mongolia.
The holotype specimen consists of the nearly complete, articulated skeleton of a small volant avialan. Apsaravis ukhaana is unambiguously differentiated from other avialans based on the presence of several unique morphologies: a strong tubercle on the proximal humerus, a hypertrophied trochanteric crest on the femur, and extremely well-projected posterior wings of a surface of the distal tibiotarsus that in Aves articulates with the tibial cartilage.
Ten other homoplastic characters optimize as autapomorphies of Apsaravis ukhaana in the phylogenetic analysis. They are as follows: ossified mandibular symphysis; dentary strongly forked posteriorly; hooked acromion process on scapula; highly angled dorsal condyle of humerus; humeral condyles weakly defined; distal edge of humerus angling strongly ventrally; humerus flared dorsoventrally at its distal terminus; lateral condyle of tibiotarsus wider than medial one; neither condyle of tibiotarsus tapering toward the midline; and metatarsal II trochlea rounded rather than ginglymoid. Phylogenetic placement of Apsaravis ukhaana as the sister taxon of Hesperornithes, Aves resulted from analysis of 202 characters scored for 17 avialan ingroup taxa. The implications of Apsaravis ukhaana, and the results of the phylogenetic analysis, for the evolution of flight after its origin and character support for enantiornithine monophyly are extensively discussed.
A. ukhaana was discovered during the 1998 field season of the Mongolian Academy of Sciences/American Museum of Natural History Paleontological Expeditions. It was recovered from the Camel’s Humps sublocality of Ukhaa Tolgod, a locality in the Nemegt Basin of southern Mongolia known for abundant, exquisitely preserved vertebrate fossils
Holtotype: IGM 100/1017. The holotype is a nearly complete skeleton in partial articulation articulation. It is comprised of the following elements: a crushed skull with a ring of scleral ossicles in the left(?) orbit; incomplete left quadrate, partial left jugal, partial mandible; 12 cervical vertebrae, 7 thoracic vertebrae; 10 ankylosed sacral vertebrae; 5 free caudal vertebrae; a pygostyle, fragmentary thoracic ribs; fragment of the anterior sternum, both scapulae; both coracoids, both humeri, ulnae, radii, radiale, right ulnare, partial right and left carpometacarpi, right phalanx one of manual digit II; ilia, ischia (right missing distal end); pubes (right, fragmentary); both proximal femora, both distal tibiotarsi; both tarsometatarsi (co-ossified metatarsals II–IV); incomplete series of pedal phalanges of digits II–IV from both feet. Several of these phalanges including three unguals were prepared apart from the main block and are preserved together in a separate, unfigured block. The distal end of the right humerus was removed from the block and prepared separately. Also, a small, midshaft section from the right radius was removed for study. (Clarke and Norell, 2002)